It is known to use jets for texturing multifilament yarn to impart crimps, curls or loops to the yarn filaments. It is also known to use air jets for interlacing the filaments of multifilament yarns. In many cases, the air jets have been used for interlacing multiple yarn ends to eliminate the usual plying operation.
The prior known types of interlacing air jets may be divided into two general types. In one type, the air is directed against the yarn passing through the jet at an acute angle. Among the several patents disclosing this general concept is the London et al U.S. Pat. No. 3,911,655 wherein the air is directed against the yarn at an acute angle of 45.degree. to 75.degree. and in the direction of movement of the yarn through the air jet.
In the other type of interlacing air jet, the air is directed against the yarn at a right angle as the yarn passes through the air jet. The Pike U.S. Pat. No. 3,983,609 is representative of the second type of interlacing air jet wherein the air is directed against the yarn at a right angle as the yarn passes through the air jet.
Both of these types of interlacing air jets appear to work satisfactorily for particular yarns. However, the interlacing of particular types of yarns requires the use of an air jet of the type which directs the air against the yarn in an angular relationship, either in the direction of travel of the yarn through the air jet or opposite to the direction of travel of the yarn through the air jet. The interlacing of other types of yarns requires the use of an air jet of the type which directs the air against the yarn at a right angle. Thus, these two types of air jets of the prior art are designed to direct the air against the yarn at a particular angle, and this angle cannot be changed, except by changing from one air jet to another.
In an attempt to provide an air jet which can be used to interlace and/or texture a variety of different types and sizes of yarn, the Roberts U.S. Pat. No. 3,823,448 discloses an air jet provided with a plurality of inserts which are selectively positioned in the jet to vary the angle at which the air is directed against the yarn. However, the use of this jet requires the removal of one insert and replacement with a different type insert each time it is desired to change the angle at which the air is directed against the yarn.